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Android实现CoverFlow效果

2012-07-30 20:59 866 查看

先上一张效果图：

上代码，看了代码什么都明白

CoverFlow从Gallery继承过来

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001	package com.coverflow;

003	import android.content.Context;

004	import android.graphics.Camera;

005	import android.graphics.Matrix;

006	import android.util.AttributeSet;

007	import android.view.View;

008	import android.view.animation.Transformation;

009	import android.widget.Gallery;

010	import android.widget.ImageView;

012	public class CoverFlow extends Gallery{

014	private CameramCamera= new Camera();

015	private int mMaxRotationAngle= 50 ;

016	private int mMaxZoom=- 380 ;

017	private int mCoveflowCenter;

018	private boolean mAlphaMode= true ;

019	private boolean mCircleMode= false ;

021	public CoverFlow(Contextcontext){

022	super (context);

023	this .setStaticTransformationsEnabled( true );

026	public CoverFlow(Contextcontext,AttributeSetattrs){

027	super (context,attrs);

028	this .setStaticTransformationsEnabled( true );

031	public CoverFlow(Contextcontext,AttributeSetattrs, int defStyle){

032	super (context,attrs,defStyle);

033	this .setStaticTransformationsEnabled( true );

036	public int getMaxRotationAngle(){

037	return mMaxRotationAngle;

040	public void setMaxRotationAngle( int maxRotationAngle){

041	mMaxRotationAngle=maxRotationAngle;

044	public boolean getCircleMode(){

045	return mCircleMode;

048	public void setCircleMode( boolean isCircle){

049	mCircleMode=isCircle;

052	public boolean getAlphaMode(){

053	return mAlphaMode;

056	public void setAlphaMode( boolean isAlpha){

057	mAlphaMode=isAlpha;

060	public int getMaxZoom(){

061	return mMaxZoom;

064	public void setMaxZoom( int maxZoom){

065	mMaxZoom=maxZoom;

068	private int getCenterOfCoverflow(){

069	return (getWidth()-getPaddingLeft()-getPaddingRight())/ 2

070	+getPaddingLeft();

073	private static int getCenterOfView(Viewview){

074	return view.getLeft()+view.getWidth()/ 2 ;

077	protected boolean getChildStaticTransformation(Viewchild,Transformationt){

078	final int childCenter=getCenterOfView(child);

079	final int childWidth=child.getWidth();

080	int rotationAngle= 0 ;

081	t.clear();

082	t.setTransformationType(Transformation.TYPE_MATRIX);

083	if (childCenter==mCoveflowCenter){

084	transformImageBitmap((ImageView)child,t, 0 );

else

086	rotationAngle=( int )((( float )(mCoveflowCenter-childCenter)/childWidth)*mMaxRotationAngle);

087	if (Math.abs(rotationAngle)>mMaxRotationAngle){

088	rotationAngle=(rotationAngle< 0 )?-mMaxRotationAngle

089	:mMaxRotationAngle;

091	transformImageBitmap((ImageView)child,t,rotationAngle);

093	return true ;

/**

097	*这就是所谓的在大小的布局时,这一观点已经发生了改变。如果你只是添加到视图层次,有人叫你旧的观念价值观为0。

*@paramw

100	*Currentwidthofthisview.

*@paramh

102	*Currentheightofthisview.

103	*@paramoldw

104	*Oldwidthofthisview.

105	*@paramoldh

106	*Oldheightofthisview.

*/

108	protected void onSizeChanged( int w, int h, int oldw, int oldh){

109	mCoveflowCenter=getCenterOfCoverflow();

110	super .onSizeChanged(w,h,oldw,oldh);

/**

114	*把图像位图的角度通过

116	*@paramimageView

117	*ImageViewtheImageViewwhosebitmapwewanttorotate

*@paramt

119	*transformation

120	*@paramrotationAngle

121	*theAnglebywhichtorotatetheBitmap

*/

123	private void transformImageBitmap(ImageViewchild,Transformationt,

124	int rotationAngle){

125	mCamera.save();

126	final MatriximageMatrix=t.getMatrix();

127	final int imageHeight=child.getLayoutParams().height;

128	final int imageWidth=child.getLayoutParams().width;

129	final int rotation=Math.abs(rotationAngle);

130	mCamera.translate( 0 .0f, 0 .0f, 100 .0f);

132	//如视图的角度更少,放大

133	if (rotation<=mMaxRotationAngle){

134	float zoomAmount=( float )(mMaxZoom+(rotation* 1.5 ));

135	mCamera.translate( 0 .0f, 0 .0f,zoomAmount);

136	if (mCircleMode){

137	if (rotation< 40 )

138	mCamera.translate( 0 .0f, 155 , 0 .0f);

else

140	mCamera.translate( 0 .0f,( 255 -rotation* 2 .5f), 0 .0f);

142	if (mAlphaMode){

143	((ImageView)(child)).setAlpha(( int )( 255 -rotation* 2.5 ));

146	mCamera.rotateY(rotationAngle);

147	mCamera.getMatrix(imageMatrix);

148	imageMatrix.preTranslate(-(imageWidth/ 2 ),-(imageHeight/ 2 ));

149	imageMatrix.postTranslate((imageWidth/ 2 ),(imageHeight/ 2 ));

150	mCamera.restore();

这个就是CoverFlow类，说明几点：
1.成员函数
mCamera是用来做类3D效果处理,比如z轴方向上的平移,绕y轴的旋转等
mMaxRotationAngle是图片绕y轴最大旋转角度,也就是屏幕最边上那两张图片的旋转角度
mMaxZoom是图片在z轴平移的距离,视觉上看起来就是放大缩小的效果.
其他的变量都可以无视
也就是说把这个属性设成true的时候每次viewGroup(看Gallery的源码就可以看到它是从ViewGroup间接继承过来的)在重新画它的child的时候都会促发getChildStaticTransformation这个函数,所以我们只需要在这个函数里面去加上旋转和放大的操作就可以了
其他的getter和setter函数都可以无视

ImageAdapter适配器：

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001	package com.coverflow;

003	import android.content.Context;

004	import android.graphics.Bitmap;

005	import android.graphics.BitmapFactory;

006	import android.graphics.Canvas;

007	import android.graphics.LinearGradient;

008	import android.graphics.Matrix;

009	import android.graphics.Paint;

010	import android.graphics.PorterDuffXfermode;

011	import android.graphics.Bitmap.Config;

012	import android.graphics.PorterDuff.Mode;

013	import android.graphics.Shader.TileMode;

014	import android.graphics.drawable.BitmapDrawable;

015	import android.view.View;

016	import android.view.ViewGroup;

017	import android.widget.BaseAdapter;

018	import android.widget.ImageView;

020	import com.gallery.R;

022	public class ImageAdapter extends BaseAdapter{

023	int mGalleryItemBackground;

024	private ContextmContext;

025	private Integer[]mImageIds={

026	R.drawable.a1,

027	R.drawable.a2,

028	R.drawable.a3,

029	R.drawable.a4,

030	R.drawable.a5};

032	public ImageAdapter(Contextc){

033	mContext=c;

036	public int getCount(){

037	return mImageIds.length;

040	public ObjectgetItem( int position){

041	return position;

044	public long getItemId( int position){

045	return position;

048	public ViewgetView( int position,ViewconvertView,ViewGroupparent){

050	ImageViewi=createReflectedImages(mContext,mImageIds[position]);

052	i.setLayoutParams( new CoverFlow.LayoutParams( 120 , 100 ));

053	i.setScaleType(ImageView.ScaleType.CENTER_INSIDE);

//设置的抗锯齿

056	BitmapDrawabledrawable=(BitmapDrawable)i.getDrawable();

057	drawable.setAntiAlias( true );

return

i;

061	public float getScale( boolean focused, int offset){

062	return Math.max( 0 , 1 .0f/( float )Math.pow( 2 ,Math.abs(offset)));

065	public ImageViewcreateReflectedImages(ContextmContext, int imageId){

067	BitmaporiginalImage=BitmapFactory.decodeResource(mContext.getResources(),imageId);

069	final int reflectionGap= 4 ;

071	int width=originalImage.getWidth();

072	int height=originalImage.getHeight();

074	Matrixmatrix= new Matrix();

075	matrix.preScale( 1 ,- 1 );

077	BitmapreflectionImage=Bitmap.createBitmap(originalImage, 0 ,

078	height/ 2 ,width,height/ 2 ,matrix, false );

080	BitmapbitmapWithReflection=Bitmap.createBitmap(width,

081	(height+height/ 2 ),Config.ARGB_8888);

083	Canvascanvas= new Canvas(bitmapWithReflection);

085	canvas.drawBitmap(originalImage, 0 , 0 , null );

087	PaintdeafaultPaint= new Paint();

088	canvas.drawRect( 0 ,height,width,height+reflectionGap,deafaultPaint);

090	canvas.drawBitmap(reflectionImage, 0 ,height+reflectionGap, null );

092	Paintpaint= new Paint();

093	LinearGradientshader= new LinearGradient( 0 ,originalImage

094	.getHeight(), 0 ,bitmapWithReflection.getHeight()

095	+reflectionGap, 0x70ffffff , 0x00ffffff ,TileMode.MIRROR);

097	paint.setShader(shader);

099	paint.setXfermode( new PorterDuffXfermode(Mode.DST_IN));

101	canvas.drawRect( 0 ,height,width,bitmapWithReflection.getHeight()

102	+reflectionGap,paint);

104	ImageViewimageView= new ImageView(mContext);

105	imageView.setImageBitmap(bitmapWithReflection);

107	return imageView;

BitmapDrawabledrawable=(BitmapDrawable)i.getDrawable();
drawable.setAntiAlias(true);
是保证图片绕Y旋转了以后不会出现锯齿.

下面是Activity：

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01	package com.coverflow;

03	import android.app.Activity;

04	import android.graphics.Color;

05	import android.os.Bundle;

07	import com.gallery.R;

09	public class HelloAndroid extends Activity{

10	/*Calledwhentheactivityisfirstcreated./

@Override

12	public void onCreate(BundlesavedInstanceState){

13	super .onCreate(savedInstanceState);

15	CoverFlowcf= new CoverFlow( this );

16	//cf.setBackgroundResource(R.drawable.shape);

17	cf.setBackgroundColor(Color.BLACK);

18	cf.setAdapter( new ImageAdapter( this ));

19	ImageAdapterimageAdapter= new ImageAdapter( this );

20	cf.setAdapter(imageAdapter);

21	//cf.setAlphaMode(false);

22	//cf.setCircleMode(false);

23	cf.setSelection( 2 , true );

24	cf.setAnimationDuration( 1000 );

25	setContentView(cf);

参考自：http://www.eoeandroid.com/thread-70209-1-1.htmlhttp://www.apkbus.com/android-18441-1-1.html

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